双壁钻杆反循环系统新型井下封阻导流器冲蚀与强度研究

井下封阻导流器的设计与优选是双壁钻杆反循环钻井的关键,针对高流速、大循环压差的工作环境,设计了一种同一本体不同井眼的井下封阻器,并对不同入口质量流速与颗粒粒径条件下进行了流体流动与封阻器磨损建模研究,依据冲蚀模拟结果对封阻器进行了强度分析,设计并进行了封阻器气密性验证与返砂实验。可看出,封隔器壁面磨损程度随着入口流量的增大和颗粒粒径的减小而逐渐增大,且根据抗拉抗扭强度要求,封阻器最大安全扭矩为29 t/m,最大安全拉力约合270t。实验结果表明,新型井下封阻导流器符合双壁钻杆反循环要求。

Study on erosion and strength of a new type of down-hole choke guide for a double-wall drill pipe counter-circulation system

The key of gas reverse circulation is the choice of blocking technology, through investigation and in-depth analysis. In this paper, considering the working environment of high velocity and large circulation pressure difference, a downhole stopper with the same body and different boreholes was designed, and the fluid flow and the wear of the stopper were simulated under the conditions of different inlet mass velocity and particle size. According to the simulation results of erosion, the strength of the stopper is analyzed. The following conclusions are obtained: with the increase of inlet flow and the decrease of particle size, the abrasion of the packer wall surface increases gradually. According to the requirements of tensile and torsional strength, the maximum safety torque of the stopper is 29 t/m, and the maximum safety tension is about 270t. The experimental results show that the new type of downhole choke meets the requirements of double-wall drill pipe reverse circulation.